The proliferation of digital cameras, camera phones, and scanners has lead to an explosion of digital images and videos, creating large personal multimedia databases. Since taking digital pictures is easy and practically free, consumers no longer restrict picture-taking to important events and special occasions. Images are being captured frequently, and of day-to-day occurrences in the consumers' life. Since a typical user has already accumulated many years of digital images and videos, browsing the collection to find images and videos taken during particular events is a very time-consuming process for the consumer.
There has been work in grouping images into events. U.S. Pat. No. 6,606,411 and U.S. Pat. No. 6,351,556 disclose algorithms for clustering image content by temporal events and sub-events. The above two patents teach how to cluster images and videos in a digital image collection into temporal events and sub-events. The terms “event” and “sub-event” are used in an objective sense to indicate the products of a computer mediated procedure that attempts to match a user's subjective perceptions of specific occurrences (corresponding to events) and divisions of those occurrences (corresponding to sub-events). Another method of automatically organizing images into events is disclosed in U.S. Pat. No. 6,915,011. The events detected are chronologically ordered in a timeline from earliest to latest.
Using the above methods, the amount of browsing required by the user to locate a particular event can be reduced by viewing representatives of the events along a timeline, instead of each image thumbnail. However, a typical user can still generate over 100 of such events for each year, and more prolific picture-takers can easily exceed a few hundred detected events per year. There is still a need to create an overall event timeline structure that is adaptable to the user's picture taking behavior as well as the time granularity of the events in their collections, and the ability to select a sub-set of events that summarizes the overall collection or a given time period in the collection.